Apparatus for hot pressing powdered metal



Nov. 18, 1947.

W. R. TUCKER APPARATUS FOR HOT PRESSING POWDERED METAL Filed Nov. 6, 1944 2 Sheets-Sheet 1 INVENTOR WARREN R. TUC KER ATTORN EYS Nov. 18, 1947. w. R. TUCKER 2,431,095

APPARATUS FOR HOT PRESSING POWDERED METAL Filed Nov. 6, 1944 2 Sheets-Sheet 2 ETE-4 INVENTOR WARREN R. TUCKER ATTORNEYS Patented Nov. 18, 1947 APPARATUS FOB HOT PRESSING POWDERED METAL y Warren R. Tucker, Dayton, Ohio, asslgnor to H-P-M Development Corporation, Wilmington, Del., a corporation of Delaware Application November 8, 1944, Serial No. 562,091

7 Claims. t 1

This invention relates tothe art of forming workpieces from finely divided metallic particles or mixtures thereof with plastics or other binders.

`This invention has for its particular object an improved method of heating and pressing the powdered material and includes the use of a high frequency electromagnetic ileld.

'This invention will be clearly understood upOn reference to the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a, press embodying the features of this invention;

Figures 2, 3, 4 and 5 are fragmentary views of the press of Figure 1 showing the operating part thereof during various stages of the pressing cycle;

Figure 6 is a view showing a modified con` struction;

Figure 7 is a view of the apparatus of Figure 6 in a different stage of the pressing cycle; and

Figures 8 and 9 are perspective views of typical workpieces adapted to be formed according to this invention.

General arrangement According to this invention there is provided a die or mold within which the powdered metal is to be compacted. A pair of pressing members are adapted to be reciprocated relative to said die so as to accomplish the aforementioned compacting.

Associated with the die and at least one of the -plungers is a heating chamber of insulating material such as ceramic or plastic within which the powdered metal is placed and heated. The heat- 4ing is accomplished by an induction coil arranged around the heating chamber and connected to a suitable source of high frequency alternating current.

Optionally, the heating chamber may also be used as the die or mold, this being possible when the tensile strength of the insulating material used therein is sumciently high to withstand the compacting force of the pressing plungers.

Structural arrangement 2 I5 which enters the said die from the right end thereof.

Arranged in coaxial alignment with the die I3 is a chamber I6 of electrical insulating material such as plastic or ceramic and preferably possessing high resistance to heat. The chamber I6 has a feed opening I1 which is adapted to receive material from the hopper I8 positioned above the said opening. The hopper I8 may include a means I9 for measuring the material into the feed opening I1 so that a predetermined charge of material may be placed within the heating chamber. The means I9 may measure the material by weight or volume as desired.

Arranged around the chamber I6 in any suitable manner is an induction coil 20 which is connected through a switch 2| with an oscillator 22 of suitable frequency and capacity for heating the material in the time desired. The coil 20 may comprise a. hollow conductor which is water cooled or may comprise a, solid conductor adapted to be air cooled, the particular job determining which type of coil will be used.

Attached to the plunger I4 is a collar 23 which is adapted, when the said plunger moves to the right, to cam over the plunger 24 which is spring urged toward the plunger I4 by the spring 25. A solenoid 26 is adapted, when energized. to withdraw the plunger 2,4 from engagement with the collar 23.

Referring now to Figure 6, there is shown a modified .arrangement wherein the material is compacted within the heating chamber. In Figure 6 the heating chamber is constructed of a high strength plastic or ceramic material capable of withstanding the compacting force of the press plungers. The chamber 30 in Figure 6 may have associated therewith, in addition to the induction coil 3l, the cooling passages 32 by which means the heating chamber and workpiece may be cooled following the pressing operation. The pressing plungers 33 and 34 may comprise end vportions of insulating material indicated at 35 and 36 which are constructed of a material suiiiciently strong to withstand the pressing force.

Referring to Figure '7, there is shown the apparatus of Figure 6 with the material compacted within the chamber 30 between the plungers 3l and 34 While the induction coil 3I is energized. It will be apparent that the portions 35 and 3i of the plungers 33 and 34 together with the chamber 30 provide an enclosure for the material which is completely electrically insulated.

1n Figures 8 and 9 are shown typical workpieces which may readily be formed according to this 3 invention. Figure 8 is a gear or similar toothed member, while Figure 9 represents a cam or other similarly shaped workpiece.

Operation The operation of the apparatus illustrated in Figure 1 is as follows:

Assuming the parts to be in the position shown in Figure l, a predetermined charge of powdered metal or powdered metal mixed with a binder is fed into the chamber I6 from the hopper I8 by actuating the measuring means I9. After the material is placed within the chamber the motors II and I2 are actuated to move the plungers I4 and I into the heating chamber so that they occupy their Figure 2 position thus compacting the powder as indicated.

Following the compacting of the powder the plungers I4 and I5 are withdrawn and the switch 2| is closed thus energizing the coil 20 from the oscillator 22 and creating an electro-magnetic ileld through the compacted material as indicated by the dashed lines on Figure 3.

When the material has reached the proper temperature for the particles thereof to be alloyed together or sintered, the switch 2l is opened and the motor I2 is actuated to move the heated material into the die I3 and compact it therein against the plunger I4. The compacting step is illustrated in Figure 4. A1; this time the plunger I4 is retained in position by the engagement of the plunger 24 and collar 23.

.After a predetermined time, during which, if desired, the die I3 may be cooled by passing a cooling medium through the passages 21, the solenoid 2B is energized to withdraw the plunger 24 from engagement with the collar 23 and the motor II is actuated to retract the plunger I4 leftwardly. The motor I2 is then effective to move the plunger I5 to the left thus ejecting the workpiece from the die I3. This stage of the pressing cycle is indicated in Figure 5.

Following the ejection of the workpiece the press parts may be returned to their Figure 1 position and a new cycle of operations commenced.

The operation of the apparatus indicated in Figures 6 and 7 is substantially the same as described in connection with Figures 1 to 5, inclusive, exceptI that the plungers 33 and 34 are not retracted during the heating cycle but remain in pressing engagement with the workpiece so that the latter is compacted, heated and sintered in a single step. The chamber 30 may be cooled during Vor subsequent to the heating and sintering step by passing a suitable cooling medium through the passages 32 should it be desired.

The completed workpieces produced according to this invention have uniform density, are of substantially the correct size when ejected, are relatively free from scale and thus require a minimum of machine work t-o produce a high quality finished workpiece.

It will be apparent that Various modifications could be made in the structure and arrangement without in any Way departing from the spirit of this invention and, accordingly, I desire to comprehend such modifications and substitution of equivalents as may be considered to come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An apparatus for heating and compacting powdered metal comprising, a mold having a cavity. therein, a, heating chamber oi electrical insulating material arranged in alignment with said mold cavity, a pair of pressing members adapted to enter said mold cavity and said heat ing chamber, an induction coil arranged around said heating chamber, means for actuating said pressing members so as to compact said powder within said heating chamber and thereafter to transfer the same into said mold cavity and compress it therein, and means for supplying electrical energy to said coil for heating said powder in said heating chamber.

2. In a press for compacting granulated metallic materials, a ceramic chamber for receiving said material, means for introducing a predetermined quantity of said material into said chamber, opposed plunger means operable at least partially to compact said material within said ceramic chamber, means including an induction coil arranged around said chamber encrgizable for inductively heating said granulated material to working temperature, a mold having a cavity therein adjacent said chamber, said plunger means being operable to transfer said material from said chamber to said cavity and to compact said material within said cavity, and means for ejecting the finished workpiece.

3. In a press for compacting divided materials at least a portion of which is metal, a mold of electrical insulating material, a pair of opposed pressing members of electrical insulating material reciprocable in said mold from opposite ends to compress material therein, feeding -mechanism operable to introduce a predetermined quantity of said material into said mold between said members, means to actuate said members to apply working pressure on said material, and means comprising an induction coil arranged around said mold energizable for heating said material therein to sintering temperature while the said pressing members continue the said working pressures.

4. In a, press for compacting divided materials a substantial portion of which is metal, a mold, a chamber of electrical insulating material adjacent said mold, said mold and said chamber having coaxial passages therethrough, a rst and a second plunger adapted to enter said passages from opposite ends thereof, means for introducing a, predetermined quantity of said material into said chamber, means selectively operable for actuating said plungers so as to Y compress said material within said chamber,

means for heating said material to working temperature within said chamber comprising an induction coil arranged around said chamber and means of supplying electrical energy thereto, means selectively operable for actuating said plungers to transfer said heated material into said mold, and means for halting one of said plungers so as the same forms a bottom for said mold while moving the other of said plungers theretoward.

5. In a press for forming workpieces from granulated metals, a heating chamber and mold chamber of electrical insulating material for receiving charges of said granulated metals, an induction coil energizable to establish a eld of electromagnetic induction in one of said chambers to heat the metal therein, and opposed pressing members movable in one of said chambers for exerting forming pressure on the granulated material therein, said pressing members being movable from opposite ends of said chambers.

5 6 6. Mechanism according to claim 5 in which the workpiece is ejected from the enclosure by REFERENCES CITED the pressing members. The following references are of record in the 7. Mechanism according to claim 5 in which file of this patent: the pressing members have at least their end 5 portions formed of electrical insulating material UNITED STATES PATENTS whereby they may exert forming pressure on Number Name Date the metal during the heating thereof without sub- 1,380,250 Reymond May 311 1921 tracting energy from the eld of the coil. 2,355,954 Cremer Aug 15, 1944 WARREN ,R- TUCKER- 10 2,362,701 Koehring Nov. 14, 1944 

